Supervision for a light display device

Abstract

A device and method may include, in a display device, emitting visible light in a humanly imperceptible manner and sensing said light to verify operation of the display device.

The invention claimed is: 
     
       1. A light display device comprising:
 a LED configured to emit light in response to power supplied thereto; 
 a photodetector disposed adjacent the LED, said photodetector configured to detect an intensity of light emitted from the LED and to generate an electrical signal that corresponds to such intensity; and 
 a control circuit connected to the LED and the photodetector, the control circuit configured to initiate a flash test to determine the operability of the LED, wherein during the flash test said control circuit is configured to activate the LED for an amount of time so that the light from the activated LED is imperceptible to a human, said control circuit further configured to receive the electrical signal from said photodetector and to determine whether the LED is operational. 
 
     
     
       2. The device of  claim 1  wherein determining whether the LED is operational comprises determining whether the electrical signal that corresponds to the intensity of light is greater than a minimum signal. 
     
     
       3. The device of  claim 1  wherein activating the LED comprises activating the LED for a flash that is less than about 15 microseconds in duration. 
     
     
       4. The device of  claim 1  further comprising multiple LEDs. 
     
     
       5. The device of  claim 1  wherein the control circuit comprises a microcontroller configured to receive an indication when the LED is activated. 
     
     
       6. A method comprising:
 initiating a flash test to determine the operability of a LED in a light display device, wherein the flash test comprises activating the LED for an amount of time that the light from the activated LED is imperceptible to a human; and 
 determining whether the LED failed to operate based on the intensity of light emitted by the LED. 
 
     
     
       7. The method of  claim 6  wherein determining whether the LED failed to operate comprises determining, by a control circuit, whether an electrical signal associated with the intensity of light of the LED is greater than a minimum signal. 
     
     
       8. The method of  claim 6  wherein activating the LED in a light display device comprises activating the LED in a dome lamp. 
     
     
       9. The method of  claim 6  wherein activating the LED in a light display device comprises activating the LED in an emergency notification strobe. 
     
     
       10. The method of  claim 6  wherein activating the LED in a light display device comprises automatically activating the LED after a set period. 
     
     
       11. The method of  claim 6  wherein activating the LED in a light display device comprises activating the LED after fabrication. 
     
     
       12. The method of  claim 6  wherein activating the LED in a light display device comprises turning the LED on for a time period of between about 1 microsecond to about 15 microseconds using a transistor. 
     
     
       13. The method of  claim 6  wherein activating the LED in a light display device comprises activating the LED for a pulse width which is imperceptible to a human.